1. Field of the Invention
This invention is in the field of stepped grate-type cooler assemblies wherein stationary grate plates cooperate with reciprocable grate plates to move the particles therealong, and the spatial arrangement is such that individual grate plates can be readily removed for replacement.
2. Description of the Prior Art
In any grate cooler, the heat exchange between the material being cooled and the cooling medium consisting of air takes place above a grate system which divides the cooler into an upper hot gas chamber and a housing base portion acted upon by the air. The grate system normally consists of a plurality of stationary and a plurality of movable grate plate carriers on each of which there are fixed several grate plates having cooling air apertures provided therein. The stationary rows of grate plates are alternated with reciprocable rows of grate plates, the various grate plates being fixed on fingers or the like extending from beams. Through the oscillating movement of all of the reciprocable rows of grate plates, the material to be cooled is transported from one end of the cooler to the other.
The grate plates, particularly those located in the recuperation zone of the cooler on which the hot material is charged undergo conditions of high wear, due to thermal and mechanical stresses. It is therefore necessary periodically to replace such individual grate plates. Damaged grate plates previously had to be released from their particular grate plate carriers and carried out from above through the hot gas chamber. It was accordingly necessary with the exchange of even a single grate plate to shut off the rotary kiln, empty the grate cooler and await the cooling off of the hot brick refractory lining of the hot gas chamber. Consequently, a long interruption of the operation of the installation was necessary before entry into the hot gas chamber and exchange of the plate could be accomplished. In addition, an exchange of grate plates of the discharge zone of the rotary kiln was particularly dangerous due to the possible dropping of glowing pieces of clinker. Such grate plates could not be removed from the bottom of the cooler because of the configuration of the carrier fingers on which the grate plates were disposed.
In order to make possible an exchange of worn grate plates from the cool, lower side of the grate, it was known from German Pat. No. 1,134,329 to construct the grate plates in two parts with a short front part which is wear resistant and heat resistant and which because of its shortness could be exchanged downwardly between the carrier fingers of the grate plate carriers. Such a two-part grate plate construction is relatively complicated and expensive. With such an installation, it is still not possible to exchange other portions of the grate plates, or indeed the entire grate plate downwardly through the cooler grate.
To make possible the exchange of entire grate plate assemblies from below a cooler grate, it is known from German Laid Open Specification No. 2,000,631 to utilize transversely lying carrier beams as grate plate carriers, and omit the carrier fingers extending in the direction of the grate feed. With these grate plates, however, only about half of the grate plate length is supported while the front half of the grate plate lies unsupported. To make the freelying grate portion resistant to bending, it is made arcuate and is reinforced by means of side flanges and ribs. These grate plates are expensive and heavy and the costs, therefore, are very high. Accordingly, these grate plates are usually inserted only in the recuperation zone of the grate cooler inlet. Such a grate cooler is therefore equipped with two different types of grate plate carrier systems and grate plate types, and accordingly the necessity of maintaining double replacement parts results in additional costs.